OF ALL OF GOLF'S mysteries, what is harder to figure than the player who shoots 78 one day and 97 the next? Or the player who goes out in 49 but comes back in 37? The same person is swinging the same way but the results are so different that it is as though cloning had produced two distinct golf games.

An easy explanation is to pass it off as sometimes-hot/sometimes-cold. This is the temperature explanation, which would be fine if human beings were thermometers.

But golf is less mercurial than that and answers can be discovered only if we examine one of the intangibles of golf - goals we set. Our sport is so much targets and aiming that we forget to go beyond the physical realities of fairways, greens and cups to the metaphysical one of goals.

Every golfer should have four kinds of goals each time he goes out: lifetime, season, round and individual shot. Goals become the skeleton on which the muscles and blood of our golf game connect, a joining that produces a structure and evenness.

A lifetime goal can be more than a lyrical hope, like one day winning the fifth flight of the member-guest or scoring a hole-in-one. My own lifetime goal is the wistful one of shooting par at Shinnecock Hills, the course that was the first ever built on Long Island and which was designed to be as much like the links of Scotland as possible. It is known, however quietly, as one of the country's most scenic courses.

I grew up hearing from my father tales of Shinnecock Hills and of his many pleasurable rounds there as a young man. My father was gone before I left Long Island playing most of its other courses but not this hallowed one. So I have it in my subconscious that Shinnecock Hills has a root or two I should pleasurably seek out.

For seasonal goals, the ordinary one of lowering our score by five ot 10 strokes is enough. It is one of life's pathetic sights to be on a golf course in October or November and see people ravaging the fairways with the samw grass-killing swings you saw them cursed with in April or May.

Their persistence is to be blessed, but after that comes the careworn question - what have they been doing out here all summer? Do they have nothing to show for walking hundreds of miles and taking thousands of swings except the stoutness of soul to endure still another round of nightmarish sevens and eights?

The 90 shooter in April ought to announce his goal of wanting to be the 80 shooter of October, and let him make a midsummer report to the universe on how it is or isn't going. That is the transcendence of golf - knowing our own wretchedness but knowing too that we are capable of eternally rising.

The goal of our next round ought to be kept to ourselves, silently expressed lest someone in the foursome bother you with it when it becomes clear you won't make it.

Instead of setting out to bring it in under a certain score, a simpler goal is to try for, say, 12 pars for the round. Or 6 or 16 pars, wahtever your skill or your ego.

After one recent prolonged layoff from golf - 36 hours - I had a chance to play a quick nine at sundown. My goal was to get five pars. Indeed I became to the ninth hole with four bogies and four pars. I drove well and had only a wedge to the green. I felt so exhilarated by the thought that I was about to reach my modest goal that I forgot how to play the shot into the green. I bladed it into the trap in front and took a bogey.

Younger golfers need to think about how many pars they want to shoot for every round because they tend to be overly concerned about scores. Let the score take care of itself, which it does anyway. The mind needs specifies. Youn can't concentrate on something so fuzzy as "breaking" 90, but you can think about something exact, like getting three pars in the next holes.

A final goal is to take each shot and visualize exactly where you'd like it to go. ben Hogan was said to be able to keep a camera image of his projected shot while he stood over the ball. This is perhaps the most difficult mental habit to acquire, but it is worth trying because it means you are aiming at a target that you can "see."

Golf is one of the few sports - yacht racing is another - where you don't look at the target while you're shooting for it. in golf, the solution is to visualize - then capitalize.

If another goal exists, it is the one P.G. Wodhouse discussed when he talked about one of golf's rare defects, the way the game "prevents a man being a wholehearted lover of nature. Where the layman sees waving grass and romantic tangles of undergrowth, your golfer beholds nothing but a nasty patch of rough from which he must divert his ball.

"The cry of the birds, wheeling against the sky, is to the golfer merely something that may put him off his putt."

Reach for that goal - watching the grass wave and the birds cry. If none of your four goals comes through you will stillbe ahead of the game, if not much in the game. What else is there?.